Portable seismometer mounted in a rugged housing can be placed in inaccessible locations and operate efficiently in other than a vertically upright position. The instrument housing contains an amplifier, transmitter, and antenna to relay measurement data to a receiving station

Lehner, F. E.

English

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Amplifier 
March 1966	 Brief 66-10085 
NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U. S. space 
program and to encourage their commercial application. Copies are available to the public from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Seismometer Designed for Remote Operation in Random Orientation 
Antenna 
Transmitter 
Sensing 
Solenoid
Pulser 
Pulser 
Signals	 Seismic 
Shock 
Signals 
I
The problem: 
To design a portable seismometer that can be placed 
in normally inaccessible locations, as by lowering to the 
ground from a helicopter or by parachute drop from an 
airplane, and that will operate efficiently in other than 
a vertically upright position. The seismometer must be 
packaged with appropriate telemetry equipment in
order to transmit its measurements to a receiving sta-
tion. 
The solution: 
A seismometer that is mounted in a rugged housing 
that contains an amplifier, transmitter, and antenna to 
relay measurement data to a receiving station. The in-
strument incorporates automatic angular adjustment 
(continued overleaf) 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19660000085 2020-03-11T17:34:03+00:00Z
.s to minimize the effect of angular error between the seis-
mic mass axis and local vertical. 
How it's done: 
The seismometer responds to local disturbances by 
measuring the relative movement of its housing with re-
spect to an inertial or seismic mass, and supplying an 
output voltage proportional to the relative displace-
ment. In operation, shocks to the casing, caused by 
slight movements of the surface the unit is resting on, 
cause the case to move in relation to the seismic mass. 
A sensing solenoid, rigidly held by the case, reacts to 
the change in plunger-to-coil relationship, and gen-
erates a signal. This signal is amplified and fed to a 
transmitter for relay to a receiving station. The seis-
mometer also incorporates a self-monitoring system 
that periodically signals the device's operational readi-
ness. This system is made up of a pulser that is timed 
to feed impulses at regular intervals to a solenoid 
whose plunger is attached to the base of the seismic 
mass. This causes the mass to move slightly in relation 
to the case and a signal is generated in the sensing sole-
noid. This signal is of slight amplitude and readily dis-
tinguished from any generated due to surface disturb-
ances because of its programed repetition rate.
Notes: 
1. The seismometer case, in the area of the seismic 
mass, may be filled with a damping fluid to with-
stand hard impact. Automatic means may be in-
cluded to vent the damping fluid following impact. 
2. Electronic components in the seismometer package 
are protected from impact damage by standard 
potting techniques. 
3. This seismometer may be dropped into bores in the 
earth or lowered to rest on the bottom of a body 
of water. The only modification required in such 
cases would be that necessary to maintain electronic 
system effectiveness. 
Patent status: 
Title to this invention has been waived under the 
provisions of the National Aeronautics and Space Act 
(42 U.S.C. 2457 (f)) to California Institute of Tech-
nology, Pasadena, California. 91109. 
Source: Francis E. Lehner, et al of

California Institute of Technology

under contract to

Jet Propulsion Laboratory

(JPL-320)
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Brief 66-10085	 Category 01


Seismometer designed for remote operation in random orientation

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